The present invention pertains to triethylenediamine adducts of certain benzoic acid derivatives and to boron trifluoride complexes with certain bicyclic amidines, and their use as catalysts in thermosettable compositions.
Thermosettable compositions are useful in many applications including for example their use as adhesive and coating compositions. Thermosettable compositions are largely based upon epoxy and/or anhydride and/or acid functionality. To prepare the thermosettable composition, the curable resin is blended with one or more catalysts. Depending upon the application, the catalyst can be designed to provide a fairly rapid cure after blending with the resin, or, the curing agent may be designed Co provide some measure of latency. That is, the thermosettable resin does not gel over a period of time, e.g. during storage, and only upon heating converts the resin from a liquid (or thermoplastic) state to a tough, hard thermoset solid.
Various compositions have been used as catalysts in thermosettable compositions. One group of curing agents includes certain complexes of Lewis acids and amines. For instance, U.S. Pat. No. 2,824,083 describes certain amine-BF.sub.3 complexes used as curing agents for polyepoxides.
U.S. Pat. Nos. 4,933,422 and 4,614,788 describe the use of certain adducts of imidazoles with organic acids having pK.sub.a values of 0.5 to 5.0. U.S. Pat. No. 2,824,083 describes the use of BF.sub.3 addition products with certain amines, amides, phenol or ether, dissolved in a liquid polyol such as a liquid polyalkylene glycol. U.S. Pat. No. 2,839,495 describes the use of the combination of an acid anhydride and a BF.sub.3 complex such as a BF.sub.3 -amine complex to resinify polyepoxides.
U.S. Pat. No.3,519,604 describes the use of a polycarboxylic acid anhydride and certain 3- or 4-amino pyridines in combination with a polyepoxy compound to form a curable composition.
Japanese KOKAI No. 64-3171A (Jan. 6, 1989) describes certain amino pyridine acid addition salts with dihydroxybenzoic acid derivatives, used as accelerators for curing epoxy resins.
Additional background information on catalysts and resins employed in thermosettable compositions can be found in U.S. Pat. Nos. 4,816,500 and 4,871,806 and European Patent Application Nos. 90308471.3 (Published Feb. 6, 1991) and 88119031,8 (Published May 24, 1989).